The single burner kerosene lantern, in your case a 639, should burn much brighter than a 285. All things being considered equal, the 639 is a much better lantern. I own a few 237 kerosene Colemans and they are the grandfather to the 639. I know for a fact that my 237 will run on both kerosene or Coleman fuel. And even regular pump gasoline, but I never suggest that unless you're going to be in a very well ventilated area. Modern pump gas has a to of nasty agents in it that you don't wanna breath as it burns.
Now, here's where things get interesting. To the OP: you can run your 285 on kerosene. I've converted mine to do so. And I'm not suggesting anything dangerous here. Coleman made a kerosene version of the 285. It was called a 214. And granted, the 214 had a unique generator that some swear was special for the kerosene, but all I did to mine was add the little preheat cup for the alcohol. Make sure you retain your heat shield because the BTUs you're going to be creating is about to greatly increase.
To me the appeal of kerosene versus a Coleman fuel/gasoline lantern is performance. And kerosene is less hazardous to store than the more volatile gasoline or Coleman fuel. CF is at least $7 a gallon now. And gasoline, although approved, will stop up a generator eventually. Plus, all the octane boosters in gasoline make it extremely hazardous to breathe burned.